Telephone system.



Patented May 2|, I901.

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TELEPHONE SYSTEii.

(Application filed Dec. 16, 1899 Renewed Apr. 11, 1901.)

(No Model.)

Caz'iiz eaae 5 M @aCa/w/ THE NORRIS PETERS Pater lted May 2|, I90l. E. E. YAXLEY & c. c. C'ADDEN.

TELEPHONE SYSTEM.

(Application filed Dec. 16, 1399. Renewed Apr. 11, 1901.)

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(No Model.)

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No. 674,867. Patented May 2|, I90l. E. E. YAXLEY &. C. 0. CADDEN.

TELEPHONE SYSTEM.

(Application filed Dec. 18, 1899. Renewed Apr. 11, 1901.)

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ERNEST E. YAXLEY, OF CHICAGO, ILLINOIS, AND CHARLES C. CADDEN, OF CLEVELAND, OHIO.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 674,807, dated May 21, 1901. Application filed December 16, 1899. Renewed April 11, 1901. Serial No. 55,439; (No model.)

To all whont it may concern;

Be it known that we, ERNEST E. YAXLEY and CHARLES C. CADDEN, citizens of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Improvement in Telephone Systems, of which the following is a specification.

The primary objects of our improvement are to enable the size to be reduced of multiple switchboards in telephone-exchanges, thereby to effect economy in the apparatus and its maintenance; to enable more perfect distribution to be made than has heretofore been possible of the work among the operators, thereby to economize in help; to reduce to the minimum liability to mistakes in connecting subscribers, and to provide a simple busy-test and an efficient signal system.

It has hitherto been found impracticable to use a multiple switchboard of a capacity greater than fromfive to six thousand, and in a multiple board of this capacity the limited reach of the operators renders necessary crowding the jacks within such small space that the various parts have to be made so small and frail that they lack durability, and the consequent massing of Wire prevents convenient access to be had to the parts of the 0 board and renders repairing diflicult and expensive. Moreover, the greater part of the apparatus is of necessity always idle, for with a set of jacks for each subscriber in an exchange according to the present practice, the

5 operator in each section of three positions,

each position usually has allotted to it seventeen or eighteen pairs of plugs, so that if the operator in the central position has all the cords of that position in use and the op- 0 erator on each side has all his plugs in use the total number of the six thousand jacks in the section which it is possible to have in use at one time cannot exceed fifty-four. The central position is the only one, however,

4; the plugs of which are all used with the jacks of the section, for the two side operators plug into jacks in the sections next to them, be-

' cause neither the first nor the third operator can reach jacks in the others position, but

must use the corresponding panel in the next adjacent. section, so that the number of jacks of a board in use at any time is really much less than fifty-four.

Our improvement enables the work of an exchange of given size to be done with amultiple board having a smaller number of jacks than has hitherto been required for an exchange of like size and enables a greater number of connections to be made with the same number of jacks than has heretofore been possible, and operators are not required to memorize the position of such a great number of jacks as they have hitherto had to memorize.

Furthermore, our improvement affords facilities for dividing up the work of connecting subscribers in a most efficient manner, and signals are so arranged that liability to mistakes and to confusion among the operators is reduced to the minimum. The subscriber gives the number of the connection wanted directly to the operator who makes the connections, thus rendering it unnecessary for the operators to repeat numbers over order -.wires to the connecting operators, whereby a great saving in time is effected and a fruitful source of mistakes is eliminated. We also provide a busy test that is extremely simple and inexpensive to maintain and is so arranged as to be perfectly separated elec- 8c trio-ally from the lines, so that inductive disturbances from them are prevented and subscribers are not disturbed when the lines are being tested.

Referring to the accompanying drawings, Figure 1 is a diagram showing our improved arrangement of lines through the multiple or calling boards and the answeringboards and the trunks between the multiple and answering boards and also the trunks leading to 0 other exchanges, besides showing the method of cross-connecting and the line'selective signals. Fig. 2 is a diagram showing in detail the wiring of a subsoribers line and one of the trunks between an answering-board and 5 a multiple board. Fig. 3 is a diagram illustrating means whereby six signals may be controlled individually from a subscribers station to designate any multiple board or class of subscribers wanted. Fig. 4 is a diagram showing a modification in the wiring of the busy-test, and Fig. 5 is a diagram showing another modification.

The better to illustrate the general plan and avoid crowding and consequent confusion, details of the busy-test, trunk-signals, and other parts are omitted from Fig. 1, but are shown in Fig 2.

As seen in Fig. 1, the incoming subscribers lines a are led through suitable main distributing or cross-connecting boards (indicated at a a) to the multiple or calling boards A and B. Only two multiple boards are shown, as being sufficient for illustration of our improvement, each for subscribers in a different class or section of telephone service and hereinafter referred to as belonging to the A class and to the B class. In larger exchanges, however, more of the classified boards may, to form a set thereof, be used, and in a small plant one is all that is required. From the multiple boards the lines lead through cross-connecting boards (indicated at a a to answering-boards, (indicated at A B'.) These answering-boards are mere switchboards, with the subscribers lines terminating upon them in spring-jacks, as indicated, and signals (drops) I) b. Trunks A 13 extend through suitable cross-connecting boards (indicated at c 0) between the answering and calling boards, each trunk A terminating at its opposite ends, respectively, in plugs A A and each plug B terminating at its opposite ends, respectively, in plugs B B and these trunks are divided 'into groups, one group for each calling-board. Similar groups of trunks (indicated at G D) lead through suitable cross-connecti ng boards 61 d to calling-boards in another exchange.

(Not shown.)

In Fig. 2, E denotes a subscribers station equipped with a set of push-buttons (indicated at 6 6 for calling and a generator (indicated at 6) adapted to deliver positive and negative pulsating currents and an alternating current. The circuits are so arranged that by pressing a push-button, as e, a positive pulsating current is sent over the Wire ff, and by pressing the other button a a negative pulsating current is sent, while if the generator 6 be operated with the hook (shown at 6 up an alternating current is sent over the wire. One sidef of the circuit leads through the contacts of the jacks on the multiple board (indicated at A) through those of the jacks on the answering-board(indicated at A) and through the two polarized signals (indicated at b b) in series, and the return side f of the circuit leads through the switchboards connecting with the sleevecontacts of the jacks on the answering and multiple board jacks and thence to the line. Thus by manipulating the proper push-button at the subscribers station and operating the generator either one of the polarized signals may be displayed at will. In the circuit of the plug A at the answeringboard A are a ringing-key g g and a listening-key g 9 with the well-known connections'shown, but with the addition to the listening-key of an extra contact 9 insulated from the listening and ringing key contacts and having a lamp or other signal g in circuit with it and connections to a battery-wire y and the signal-wire so, which latter terminates in the sleeve h of the plug A The plug A isassociated with a socket-switch (indicated at A consisting of a movable member 01, connected to a signal-Wire W, a contact j, connected with the positive pole of a battery T, and a contact 70, connected with the negative pole of that battery. The plug A is similarly associated with a socket-switch (indicated at A consisting of a movable member 1', connected with the signal-wireW through a signal S, and two contacts j and 7c. The contact j is connected with a pilot-relay Z, controlling a lamp-signal Z, and with the positive pole of the battery T, and the contact is connected with the negative pole of said battery through a pilot-relay m, controlling a lamp-signal m. The tip and ring contacts of each plug are connected in the usual way, and in the circuit of the callingboard A is included a test-key F F, which is Wired as follows: from the two contacts at F F, which are adapted to be connected with the respective sides of the line,wires w to lead to the secondary 4.0 of the operators induction-coil and head-receiver 'n. in series and by a branch 10 to the middle of the testwinding 20 which is in inductive relation to the secondary. A transmitter-circuit G is arranged With the primary winding 10 in the usual way. From the ends of the test-coil w wires to and to lead through resistances R and R, Which should be regulable, respectively, to the positive poles of test-batteries X and Y. The test-circuit of the line is taken from the negative pole of the battery Y through the cont-acts and the test-pieces o of the jacks on the boards A and A in series to the negative pole of the battery X. The signal m, controlled by the pilot-relay m, and signal l, controlled by the pilot-relay Z, are each supplied by the mains T and T of battery T, which also supplies relays p and q, controlling clear-out signals, (indicated at p and q.) At the answering-board A the trunk is divided into twoparts by condensers (indicated at r and 0") connected in series with the line. The relays p and q are provided each with a line-coil s and an auxiliary coil 3. The line-coils are in bridge connection across the line, one in each part, as indicated, and the auxiliary coils are connected to the battery-mains T and Wire W through the relay-contacts p and (1 respectively, the corresponding signals 29 and q, contacts 19 and (1 the signal-wire W, and the contacts j and j.

The operation is as follows: A subscriber intending to call another, first ascertains the class, as A or B, and the number therein of the subscriber he wishes to call. If the subscriber wanted is, say, in the A class, the calling subscriber presses the proper button e on his instrument and turns the generator-crank. This throws the polarized drop 5, designating the group of trunks A on the answering-board A, but does not afiect the polarized drop I), designating the group of trunks B as the subscriber will have sent over the line a current capable of operating the drop I), but to which the drop Z) is inoperative. The exchange-operator then knows that a subscriber in the A-board class is wanted and inserts a plug A belonging to a trunk of the group A into the jack of the called subscriber, thereby opening the signalcircuit to the drops and opening the busy test circuit to put the busy-test on the line. Removal of the plug A from its socket will have caused the spring 1' to break connection with the contact 7t and to close against the contact j, thus causing current to flow from the battery-main T on signal-wire W through the signal S, over spring 6 and contact k, and through the pilotrelay m to the battery-main T. The operator at A seeing the pilot-signal m displayed, which is a general signal for all the cords in that position and is controlled by the relay in, knows that some cord is to be connected with some line, and the signal S, being associated only with the plug A designates that it is that plug on which a connection is wanted. Thereupon the corresponding listening-key F F is operated and the operator inquires of the subscriber the number wanted, and when this has been ascertained the operator touches the test-piece 0 of the jack of the number wanted with the tip of the plug A Should the result he that the line called for is found to be busy at one of the upper jacks on the board A, the ring contacts 0 of that jack will be open and current will flow from the tip of the plug A to the test-piece 0 of the jack under test in the middle position on the board to the battery X and lower half of the test-coil 10 through branch to, wire 10, and contact F of the testing-key back to the tip of plug A Should the line called for be busy at one of the lower horizontal series of jacks on the calling-board A, the contacts 0 of that jack will be open and current will flow from the tip of plug A to the test-piece 0 of the jack under test in the middle position on the board, through the contacts 0 of the last-named jack, through the contacts 0 of the upper jacks, battery Y, and upper halt of the test coil 10 and over branch 10, wire to, and contacts ot the listening key F F back to the tip of plug A Thus in either case the secondary '20 will have been inductively affected by the energized section of the test-coil w ttild. a click produced in the operators receiver, notit'ying the operator that the line asked for or under test is busy. Should the line asked for not be in use, current will flow from the batteries X and Y to the test-piece o of the jack under test, thence to the tip of the plug A with which the test-piece is touched, through one side of the listening-key F F to the center of the test-coil Q05, over which it divides equally and differentially around the core of the coil to the resistances R R, employed to adjust the balance, and to the opposite poles of the batteries X and Y. As the current will have passed equally and differentially around the core of the operators coil, no effeet is produced upon the secondary 10 there of, and the line tested will be found to be not busy, so that the plug may be inserted. When a sleeve h and a test-piece oare brought into contact by the insertion of a plug into a jack, current flows from the battery-main y through signal g contact 9 controlled by the listeningkey g g (and which is kept closed by the operator, as the key is in listening position to enable it to be ascertained when the party called has answered,) signalwire as, sleeve 71, and test-piece 0 along the test-circuit to the negative pole of the battery X. This causes the signal g to be displayed and notifies the operator at A that the connection has been completed, whereupon that operator rings with the key g g to call the subscriber wanted. hen conversation begins between the two subscribers thus connected, the operator at A releases the listening-key g g whereby the signal g is restored. The operator at A then supervises the call, and the operator at A is relieved of all ringing, &c., as soon as the connection has been made.

The condensers r 1*, while of a capacity sufficient to transmit speech, effectually stop the greater part of the signalingcurrent from the subscribers station and force it through the relay in that part of the line in which the current originated. Thus when either subscriber signals the operator to disconnect the line by operating the generator at the telephone with the hook up the line-coil ol the clear-out relay p or g is energized. This causes the armature-contacts to close and the respective auxiliary coil to be energized by current from the battery-main T and wire W flowing through the signal 1) and q and the respective signal to be displayed, and the relay is locked and the signal continuously displayed until the circuitis opened, as by separating the contacts 19 g or by replacement of the plugs A A and the consequent opening of the auxiliary-coil circuit to the battery-main 'l and coutactsj andj. Thus when either subscriber rings ol't' the operator knows which it was, and if it be the one who was called and no ring-off signal follows from the calling subscriber the wish of the latter will be inquired; but should another connection be wanted the operator may order it from the multiple operator of the class containing the subscriber ascertained as the result of the inquiry. If both subscribers ring off, the operator at A removes the plug from the jack on the board A and restores it to its IIO IZO

socket, thereby causing the spring 2' to break contact with the contact j and close against the contact 70, and current to flow from battery-main T Over signal wire W, through signal S, spring 1', contact j, and relay Z to battery-main T and thus cause the general signal Z to be displayed, notifying the operator at A that some plug requires to be removed from a jack on the multiple board. The signal S designates the individual plug, which is then removed and replaced in its socket, thereby causing the spring 2" to break contact with the contact j and close against the contact lo, thus giving to spring t the same potentialasspringaand has both springs are then in connection with the battery-main T current ceases to flow and the signals are restored.

In Fig. 3 the generator e, which is adapted to produce positive and negative pulsating currents and also an alternating current, has in circuit with it the six push-buttons 6, e e e c and e, arranged, as shown, to make different combinations with the two sides of the line and ground and the terminals of the generator to operate signals indicated at e, e e e 6 and e, which may be polarized in any well-known manner. Thus the button e connects Wire L of the line to the positive terminal of the generator and wire M to the negative terminal thereof. This operates the signal a, which is sensitive to current in that direction; but signal (2 is not displayed, not being responsive to the afore said combination, while the remaining four signals are not traversed by current and therefore remain passive. In like mannerthe signal 6 may be operated from the pushbutton 6 by a current flowing in the opposite direction to that for operating the signal a and the latter is not thereby operated. The buttons 6 and 6 give similar combinations with the wire L and ground, and the buttons 6 and 6 give similar combinations with the wire M and ground. Thejacks, one of which is represented at 0 are connected in the line with the sleeve-contact spring of each in a branch connection, while the tip-spring opens a contact which cuts off the apparatus in the line beyond it, so that when a plug is inserted the respective signal has only one connection with the line, which is on the sleeve side. Then if a current is sent over the wires L and M it cannot operateany of the signals, and by giving the signals a high coefficient of induction all disturbances from the ground connection may be prevented. The hook e is arranged to close the wires L and M on the alternating-current terminals of the generator when in theupper position, and this combination is used to actuate the clear-out signals in the cord-circuit.

In Fig. 4 We show another way of wiring our busy test, involving the same principle as that hereinbefore described of a balanced current flowing through devices arranged to give no signal when all the contacts of the test-pieces of the spring-jacks are closed, but to respond when the resistance of one side of the circuit is thrown out of balance by having its resistance raised or by being opened altogether. We omit the details of the wiring of this circuit in conjunction with the cord-circuit, as they are the same as shown in Fig. 2, and any one skilled in the art will readily understand how they may be applied in practice. At 0 is indicated the test-piece of each jack, of which 0 denotes the contacts, adapted to be actuated by a member of the spring-jacks controlled by the plug, as the sleeve-contact 0 These are all in series, as shown, and are connected with the test-coil t of the operators set, which is divided in the center and from which a connection is taken, as shown, through the battery 25 to the testplug, (indicated at 25 or, as in practice, through the tip side of the operators listeningkey (not shown) to the tip of the cord-circuit plug. (Not shown.) The operation is as follows: When there is no plug in any jack on the line, all of the contacts 0 are closed, and if the test-plug t be applied to any test-piece 0 current from the battery 15 will flow equally from the plug 25 through the test-piece 0 and contacts 0 to both of the outer terminals of the test-coil t (since both of the circuits thus formed are arranged to have approximately the same resistance) and back to the battery. As the current flows through both sides of the coil tin different directions as regards the core, no effect is produced on the secondary t containing the operators-head receiver, as indicated. If, however, a plug be in one of the jacks, as in the instance where the line is so connected with another, some one of the contacts 0' will be opened by the plug through the medium of a sleeve contact spring 0 and the piece of insulation 0 which transmits motion to the spring 0 separating it from the test-piece and opening the contact. Then if the test-plug be applied to one of the test-pieces 0 it will not cause two circuits to be formed, as the open contact will break one of them and the current will only flow through one helix of the test-coil t, and as the latter is not neutralized by current in the other helix it will affect the operators secondary inductively and cause a click in the operatorsreceiver.

In Fig. 5 is represented still another modification on the same principle Where relays are used. This modification is more especially applicable to large multiple boards where the number of jacks, and consequently the number of contacts, is very large and liable to render impracticable the close adjustment required of the resistance of the circuits for the differential coil. We then use two relays, as this allows of a comparatively wide variation of the resistance of the circuits without interfering with the efficiency of the test. Two relays i and are substituted, respectively, for each half of the differential coil 25 of Fig. 4:.

The two armatures 15 and are connected together by a winding 25 on the operators coil, and the upper contacts it and it are connected together at one pole of the battery Z, and the two lower contacts a and a are connected together at the opposite pole of the battery Z. Batteries Z and Z of equal voltage may he placed, as indicated, with their polarities opposed, or one battery (indicated at Z may be used in the wire leading to the test-plug. In operation if there be no plugs in the jacks all the contacts 0 will be closed, as hereinbefore explained with reference to Fig. 4, and the test-plug when applied to the testpiece 0 of a jack will supply current to two circuits, one'froni the test-piece in contact with the test-plug through the battery Z and relay i and the other through the battery Z and relay 6 Both armaturest and it will be attract-ed simultaneously and will close against the two upper contacts u and a, in doing which they are given the same potential, and there is no tendency for current to flow in the coil and no effect is apparent in the operators receiver a. When the contact is broken between the test-plug and test-piece, the current ceases to flow through the relays, and the armatures, being released, engage with the contacts a and u Then both armatures are again of equal potential on the opposite side of the battery Z, and again there is no tendency of current to flow through the coil t and no effect is produced therein. If, however, one of the contacts in the testcuit be opened by a pluginserted into one of the jacks, as explained in connection with Fig. 4:, there will be only one circuit for the current from the test-plug and only one of the relays will be actuated. Then the armature of, say, the relay 15 is attracted, contact a is closed, and the circuit of battery Z is completed as follows: from the positive pole through contact to, coil and contact a to the negative pole of the battery. The secondary of the operators receiver is inductively affected, and a click is produced in the receiver which the operator understands to signify that the line under test is busy.

What we claim as new, and desire to secure by Letters Patent, is

1. In a telephone system, a spring-jack provided with a branch terminal to the sleevecontact, a ti p-contact adapted to open the line when actuated by a switchboard-plug, a testpiece, and a separate contact-spring actuated by a member of the jack controlled by a switchboard-plug and normally in contact with said test-piece, but separable therefrom when actuated by a switchboard-plug, substantially as described.

2. In a telephone system, the combination of a switchboard equipped with multiple spring-jacks having test-pieces and springcontacts normally in connection therewith and adapted to be controlled by switchboardplugs, the contacts of all the jacks of each individual telephone-circuit being wired in sel'les, a circuit leading from the test-piece of the first jack in each series to the spring-contact of the last jack in such series, and a branch leading from a point in said circuit to a suitable contact-terminal. such as a switchboard-plug, wherehythe normal single circuit through the spring-jack test-pieces and return-wire may be divided into two circuits with the said branch to said switchboard-plug and one of the test-pieces forming a return common to both of said circuits.

In a telephone system, the combination of a switchboard equipped with multiple spring-jacks having test-pieces, and springcontacts normally in connection therewith and adapted to be controlled by switchboardplugs, the contacts of all the jacks of each individual telephone-circuit being wired in series, a circuit leading from the test-piece of the first jack in each series to the spring-contact of the last jack in such series, a branch leading from a point in said circuit to a suitable contact-terminal, such as a switchboardplug, whereby the normal single circuit through the spring-jack test-pieces and return-wire may be divided into two circuits with the said branch to said switch board-plug and one of the test-pieces forming a return common to both of said circuits, and one or more sources of current disposed in said circuits to prevent the flow of current when only the normal single circuit exists, whereby completing said double circuit causes current to flow in both circuits in the same direction to said branch wire and opening of said two circuits causes current to flow only in one of them.

at. In a telephone system, the combination of a switchboard equipped with multiple spring-jacks having test--pieces and springcontacts normally in connection therewith and adapted to be controlled by switchboardplugs, the contacts of all the jacks of each individual telephone-circuit being wired in series, a circuit leading from the test-piece of the first jack in each series to the spring-contact of the last jack in such series, a branch leading from a point in said circuit to a suitable contact-terminal, such as a switchboardplug, a test device in said circuit, and one or more sources of current disposed in said circuit to prevent, with the normal single circuit, said device from being actuated to give a signal and, when the double circuit is completed, to cause the device in both circuits to be actuated simultaneously, whereby no signal is given, while when one of the sides of the double circuit is open, as by opening one of the said contacts, the device in only one of the circuits is actuated and a signal is given.

5. In a telephone system, the combination of a switchboard equipped with multiple spring-jacks having test-pieces and springcontacts normally in connection therewith and adapted to be controlled by switchboardplugs, the contacts of all of said jacks of each individual telephone-circuit being wired in series, a circuit leading from the test-piece of the first jack in each series to the spring-contact of the last jack in such series, an induction-coil winding in said circuit, a branch leading from the middle of said winding to a suitable contact-terminal, such as a switchboard-plug, and one or more sources of cur-- rent disposed in said circuit to prevent the flow of current through said winding when only the normal single circuit exists, and to cause completing of said double circuit to produce flow of current differentially in the two sections of said winding, thus producing no inductive effect on the core of the induction-coil, and opening of one of said two circuits to produce flow of current in only one section of said winding thereby magnetizing the core of the ind notion-coil to generate current in the other winding and actuate the signal.

6. In a telephone system, the combination with the calling and answering boards and the telephone-lines thereon, of a trunk-circuit extending between said boards and terminating in-plugsfor the respective boards, ringingkeys for ringing out, one for each plug, a lis tening-key in the trunk-circuit at the answering-board and a listening-key having a tapcircuit extending from its tip side to the center of the test-winding of the induction-coil in the operators circuit, the terminals of said test-coil being connected with the two negative sides of the test-batteries, whereby the answering operator may plug into a line calling for a connection, the calling operator may receive the order from the subscriber, test the circuit of the line wanted and complete the connection, and the answering operator may do all the signaling of subscribers and otherwise supervise the call.

7. In a telephone system, the combination with the calling and answering boards and the telephone-lines thereon, ofa trunk-circuit extending between said boards and terminating in plugs for the respective boards, the callingboard plug being adapted to complete three contacts, two for the telephone-line and one at the test-piece of a spring-jack on the calling-board, a signal at the answering-board in circuit with the third contact of the callingboard plug, an operators listening-key controlling contacts in said circuit, and a testbattery through which said circuit leads back to said test-piece, whereby the operator at the answering-board may, by throwing the listening-key, ascertain Whether said calling-board plug is in a jack, substantially as described.

8. In a telephone system, the combination of a source of signaling-current at a subscribers station, suitable conductors between said station and an exchange-switchboard, spring jacks on the switchboard connected to said conductors, acord-circuit terminating in suitable plugs, two signals each in a separate bridge connection across the two sides of the cord-circuit, and condensers in series with the cord-circuit between the two bridge-circuits, whereby voice currents may pass through said cord-circuit, but the signalingcurrents from the subscribers station are compelled to pass through the signal in the bridge on the side of the cord-circuit at which the current originates.

ERNEST E. YAXLEY. CHARLES C. GADDEN. In presence of M. J. FRosT, F. J. MARTIN, 

